1. Field of the Invention
This invention pertains to a networking apparatus for conducting data communications among a plurality of processing apparatuses, and more particularly to a networking apparatus capable of enabling other processing apparatuses to conduct subsequent data communications, when a processing apparatus on a data origination side stops.
2. Description of the Related Arts
Recently, as requests for data communications systems become ever more diverse and advanced, networks each accommodating a large number of processing apparatuses have begun to exchange communications data on a mutual basis. As systems become ever more highly integrated on a larger scale, their maintenance functions become even more critical.
FIG. 1 is a block diagram showing a system configuration of a conventional networking apparatus.
A networking apparatus 100 is connected with a plurality of processing apparatuses, each of which having equal functions. Assume here for the sake of convenience that a group of data origination side processing apparatuses 110 (comprising a plurality of data origination side processing apparatuses 110-1, 110-2, . . . ) transmits data packets and that a group of data termination side processing apparatuses 120 (comprising a plurality of data termination side processing apparatuses 120-1, 120-2, . . . ) receives the data packets. The networking apparatus 100 has a switching unit 130, which forms paths for the data packets between the group of data origination side processing apparatuses 110 and the group of data termination side processing apparatuses 120, under control of the networking apparatus 100 for executing data communications.
FIG. 2 illustrates the contents of a data packet transmitted in data communications.
The head end of the data packet stores an apparatus identification (ID) 200 for designating a receiving one in the group of data termination side processing apparatuses 120. The tail end of the data packet stores an end-of-data signal (E) 210.
The description of the related arts continues by returning to FIG. 1.
On detecting the apparatus identification (ID) 200 at the head end of a data packet transmitted from one in the group of data origination side processing apparatuses 110, the networking apparatus 100 selects one in the group of data termination side processing apparatuses 120, and sets a path in the switching unit 130 for transmission of the data packet to the selected one in the data termination side processing apparatuses 120. On transmitting the end-of-data signal (E) 210 at the tail end of a data packet transmitted from the one in the group of data origination side processing apparatuses 110, the networking apparatus 100 cancels the path, thereby consummating a transmission of the data packet. That is, a reception of the apparatus identification (ID) 200 and the end-of-data signal 210 in a data packet causes the networking apparatus 100 to set and cancel a path for the data packet, respectively.
Assume here that the pertinent one in the group of data origination side processing apparatuses 110 stops during data communications, for instance. Although this one in the group of data origination side processing apparatuses 110 aborts a data packet currently being transmitted, because the networking apparatus 100 has not received an end-of-data signal (E) 210, the networking apparatus 100 cannot cancel the path in the switching unit 130.
When the path of an aborted data packet remains set in the switching unit 130, an attempt by another one in the group of data origination side processing apparatuses 110 to transmit a data packet to the same one in the group of data termination side processing apparatuses 120 causes the networking apparatus 100 to hang up, due to an inability of the switching unit 130 to set a path to the same one in the group of data termination side processing apparatuses 120, since the path of the aborted data packet between the stopped one in the group of data origination side processing apparatuses 110 and the same one in the group of data termination side processing apparatuses 120 remains set. A replacement of the stopped one in the group of data origination side processing apparatuses 110 does not enable the path to be reset, because the networking apparatus 100 waits for the remainder of the aborted data packet.
Consequently, the conventional system shown in FIG. 1 requires the networking apparatus 100 to have the switching unit 130 reset its paths entirely, when any one in the group of data transmission side processing apparatuses 110 stops.
The above described conventional system requiring the networking apparatus 100 to have the switching unit 130 reset its paths entirely upon stop in one in the group of data origination side processing apparatuses 110 has a serious problem. This is because the complete reset of paths by the switching unit 130 causes the networking apparatus 100 to suspend all jobs related to data communications between other processing apparatuses by data packets transmitted along other paths.